BAN103, a pollen-preferential gene, from Chinese cabbage and its promoter activity

We isolated and characterized a pollen-preferential gene, BAN103, from Chinese cabbage and analyzed the activity of its promoter. The BAN103 cDNA and genomic clone that contained the full-length gene were sequenced. The BAN103 gene is a single copy in the Chinese cabbage genome, and divided into three exons by two introns. The deduced sequence of 68 amino acids showed a homology with the Brassica oleracea pollen coat protein, as well as several cold-induced proteins. BAN103 transcription was restricted in anthers, but not in pistils, sepals, or non-reproductive tissues. Its transcription is also regulated developmentally. It was first detected after microspore releasing; it increased until the pollen matured. The BAN103 gene promoter was fused with a GUS structural gene. This recombinant plasmid was transformed to Chinese cabbage and tobacco. The GUS expression was detected pollen-preferentially in transgenic tobacco plants. The pollen-preferential activity of this promoter was retained within 176 bp from the translation start codon. The GUS transcription and translation were not coincident in transgenic tobacco pollen. GUS transcripts appeared just after microspore release, and that translation started as the pollen began to dry in mature anthers.